This Proposal is designed to analyze the determinants of individual demand for Human Immunodeficiency Virus (HIV) testing. Very little is known about the demand for HIV testing in the general public. However, since August 1987, date about AIDS knowledge and attitudes has been collected as a supplement of the National Health Interview Survey (NHIS). The NHID AIDS Knowledge and Attitudes Survey provides a large, national sample of the general population chosen on a random basis. Several reports of provisional data from the survey have been released by the National Center for Health Statistics, but they provide simple descriptive information only. There are no cross tabulations to determine interactions of variables and there is no modelling of the determinants of demand. The purpose of this proposal is to do analytical research on the demand. The purpose of this proposal is to do analytical research on the factors which affect demand for HIV testing and to simulate future demand. This study will use the NHIS data to:1) study the determinants of voluntarily initiated individual demand for HIV testing by analyzing the characteristics of who is tested or plans to be tested, 2) study the utilization of testing by those who have been or will be tested by examining how many times they are tested, why they are tested, and where they go to be tested, and 3) analyze the changes in demand for testing over time, using data from the NHIS for 1987-1989. Our model predicts that an individual's demand for HIV testing is a function of sociodemographic factors, risk factors, and knowledge of AIDS and HIV testing. Three measures of demand for testing will be used: 1) whether or not the individual elects to be tested, 2) selection of the testing site, and 3) number of testing episodes during the year. Multivariate regression analysis, Tobit, Probit and/or logit will be used to examine these relationships. Results of the study will contribute to a better understanding of the determinants of individually initiated demand for HIV testing. The results can be used to plan for future testing and educational services, will be a crucial component of future studies of the supply, demand, and costs of HIV testing, and will provide useful information in predicting the future course of the epidemic.